Barry,
I don't know if the pipe is solid or just rolled and not joined. I'd imagine, being so thin butted together and soldered maybe.
I have not seen Gordon's gun "in the flesh" as it were.
Some were also altered and a screw used, threaded into the barrel lug.
I have one altered in this manner.
Below is an on-line photo of this adaption, plus one of the lug on my gun;
Best,
R.
My gun is a bit of a mystery, as the forward ramrod pipe is Very small in diameter, and will only take a 1/4" rod at best. Maybe a iron or baleen rammer was used.